This invention relates to ink-jet printer and printing method which perform printing by discharging ink from an ink-jet head onto a printing object, an auxiliary member, an ink-jet head, a warp correction method, an ink-jet head unit and color-mixture reducing method.
In recent years, there is an increasing need for liquid-crystal displays, and especially for color liquid-crystal displays, with development of personal computers, and especially handheld personal computers. However, it is necessary to reduce cost of the liquid-crystal displays so that the personal computers can be more widely used. Especially, it is required to reduce cost of the color filter which is considerably expensive. Conventionally, various methods have been practiced to meet the above requirements while satisfying the necessary characteristics of color filter, however, none of the methods satisfies all the necessary characteristics. The previous methods are as follows.
The first method is a pigment diffusion method. This method obtains a single-color pattern by forming a photosensitive resin layer where pigment is diffused on a substrate and followed by patterning of the resin layer. This process is repeated three times to form an R, G and B color filter layer.
The second method is a coloring method. This method obtains a colored pattern by coating water-soluble polymeric material, as coloring material, on a glass substrate, forming it into a desired pattern by photolithography process, and dipping the obtained pattern into a coloring bath. This process is repeated three times to form an R, G and B color filter layer.
The third method is an electrodeposition method. This method performs electrodeposition of a first color by forming a transparent electrode into a pattern on a substrate and dipping the electrode into an electrodeposition coating liquid including pigment, resin, electrolyte and the like. This process is repeated three times to form an R, G and B color filter layer, and finally, the color filter layer is sintered.
The fourth method is a printing method. This method forms a colored layer by diffusing pigment on a heat-setting type resin by printing three times for coloring R, G and B, and heating the resin to set.
Generally, a protective layer is formed on the colored layer in any of these methods.
The above methods repeat one process three times to color the three R, G and B colors, which increases cost. Further, as the number of processes is great, the yield is lowered. Further, the electrodeposition method, in which the formable pattern shape is limited, cannot be applied to a TFT (Thin Film Transistor) without difficulty by using the present technique. Further, the printing method with poor resolution and smoothness cannot be employed to form fine pitch patterns without difficulty.
To compensate these drawbacks, Japanese Patent Application Laid-Open Nos. 59-75205, 63-235901, and 1-217320 disclose manufacturing a color filter by using an ink-jet printing method. According to these conventional arts, ink including three R (red), G (green) and B (blue) color matters is discharged onto a light-transmitting type subject in accordance with an ink-jet method, and the respective color ink is dried to form colored image portion. The ink-jet method enables formation of R, G and B pixels in one process, thus greatly simplifies manufacturing process and greatly reduces cost.
A known ink-jet method is so-called bubble-jet method which causes film boiling by thermal energy to form a bubble and discharges ink by volume expansion of the bubble. In a case where the bubble-jet method is applied to an ink-jet head, the temperature of the ink-jet head increases due to the thermal energy. The temperature rise expands the ink-jet head, which may shift the positions of discharge nozzles for discharging ink. Recently, a long ink-jet head where a large number of nozzles are arrayed is employed, and the ink-jet head is scanned in a direction approximately orthogonal to a direction along the array of the nozzles for coloring a large number of pixel arrays at one scanning. The shift of the positions of the discharge nozzles due to expansion of the ink-jet head in its lengthwise direction is a serious problem.
Further, in the above long ink-jet head, it is difficult to manufacture a head such that a large number of nozzles, .mu.m order apart, are arrayed in one line. Especially, when high-precision ink discharging is required as in manufacturing a color filter, it is very important to improve positional precision of the nozzles.